1. Field of the Invention:
The present invention relates to optical fiber technology. More specifically, the present invention relates to techniques for dispensing fiber from a bobbin.
While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility.
2. Description of the Related Art:
Certain applications require high-speed dispensation of fiber from a bobbin. One such application involves the optical guidance of missiles and other craft. In such applications, the fiber is typically dispensed from a tapered bobbin. The taper is typically on the order of two degrees and facilitates high-speed payout while mitigating multiple-turn and multiple-layer dispense. Multiple turn dispense involves the pay-out of multiple turns in the outermost layer due to the use of adhesives. Multiple-layer dispense involves the pay-out of a layer that is in the middle of the fiber cable during the payout of a surface layer. Multiple-layer dispense occurs when the cable that is being paid-out catches a section of cable in the area of an aft layer transition (optical fiber stepback) on the bobbin. Either of these anomalies may cause the cable to become entangled and break.
Unfortunately, there are several shortcomings associated with the use of a tapered bobbin. Firstly, the fiber, wound under tension, has a tendency to move down the tapered bobbin to reach a lower energy state. This necessitates the use of glues and/or other schemes to keep the cable in place. Nonetheless, gross movements of the cable pack have been experienced with tapered bobbins.
Secondly, the design and manufacture of the base layer is critical for tapered bobbins. The base layer is a layer on the surface of the bobbin on which the fiber is wound and is typically a wire having a diameter 2% larger than the cable diameter. The base layer determines the "pitch" of the fiber, that is, the spacing of each turn of the fiber and transmits the fiber pack loads to the bobbin. Tapered bobbins generally require wire base layers which are expensive to manufacture, requiring the wrapping of precision drawn wire around the bobbin.
Thirdly, tapered bobbins are difficult and expensive to manufacture. Each design is a function of such factors as the speed of dispensation, whether the bobbin is moving or stationary, and whether the bobbin is intended for operation in the air or in the water. In addition, the diameter of the bobbin and optical cable diameter impacts on the taper, thus, there is no simple technique for designing the taper of each bobbin.
In addition, the use of a taper requires the winding of the fiber with the layer transitions mentioned above. This precludes the use of certain autowinding techniques and therefore necessitates a relatively slow and costly winding operation. The required transitions also lessen the volumetric efficiency of the bobbin, i.e., lessens the amount of cable that may be wound within a proscribed volume.
As mentioned above, the tapered bobbin requires adhesives. The tapered bobbin also provides limited control of post peel point friction and provides no buffer between the peel point and paid-out fiber at the aft layer transitions.
Thus, there is a need in the art to provide an improved fiber dispenser. More specifically, there is a need in the art to provide a nontapered fiber dispenser.